Larry: Underwood may be shooting you straight.
When I worked for AeroJet in Sacramento they were winding 2nd stage "Peace Keeper" motor cases with "Pre-preg Kevlar Filament Roving" The most importent reguirement was that it be conditioned in a 20% RH environment after being prepreged with Resin because moisture levels above that lead to delaminations in the wound cases.. That ment a humidity controled environment which was very expensive to do with refrigeration. I inquired as to what the maximum temperature was that the roving could be continuously exposed and was told 150 Deg. F. I determined that in Sacramento if it were stored at 135 Deg. F we could keep it below 20% RH. because the 99% design wet bulb was 71 Deg. (if I remember right in Sacramento) We had to control the absolute humidity in the winding area to 63 gr. of water per lb of air and the winding was heated to with "Heat Lamps" to a point where the resin matrix was activated and the roving would bond together. I am not knowledgeable of the system details as much of it I think was classified and may still be. So in short humidity levels can have a huge impact on composit resin behavior. In short I suspect what A. Underwood says may well be true and his anecdotal evidence seems to bear him out. Don Burlington, IA AUnderwood wrote: > Hay guys. I had the same problem and have had it off and on several times. > How humid is it? I called aeropoxy and they said to try one trick. Take a rag > and put MEK on it and and lighty wipe the surface. When it won't get hard > because of mosture its called blushing. I don't know if age has anything to > do with it. But call them to be sure or try a spot thats not important. One > thing i found that works good is to build a tent over whatever your working > on after the layup and put one of thoes electric oil filled radiator heaters > under the tent. No open flame and you can regulate the temp. I've hade it up > over a 100 degrees. The aeropoxy people said the hotter its cured the more > restant it is to heat after its cured.Anyway hop that helps. > > -----Original Message----- > >From: larry severson <lar...@socal.rr.com> > >Sent: Jul 20, 2006 6:42 PM > >To: KRnet <kr...@mylist.net> > >Subject: Re: KR> Aeropoxy Chameleon > > > >At 09:54 AM 7/20/2006, you wrote: > >>It will not set up for me. It has stayed sticky for a week now. > > > >The mixture ratios for ANY epoxy must be EXACT. I suggest that your > >mixture ratio is off. > > > > > >Larry Severson > >Fountain Valley, CA 92708 > >(714) 968-9852 > >lar...@socal.rr.com > > > > > >_______________________________________ > >Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > >to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > >please see other KRnet info at http://www.krnet.org/info.html > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
